1. Your son's ALO "KNOWS" he got accepted to Summer Seminar
2. Thus; you son's ALO "KNOWS" he is still very interested. (Or your son wouldn't have applied for summer seminar)
3. Your son's ALO most likely requested that you wait for the interview, because he's probably still busy with his current list of applicants. I know I am. Some received an appointment; I'm helping them with the paperwork. Some didn't receive an appointment and they may be trying to determine if they should try again. So it's possible that your Son's ALO is still busy. "PLUS, for most of us, it's a volunteer job. We have "Real" jobs that we do also to pay the bills.
4. Once your son completes 3 action items on his academy application, the academy will send a suspense to the ALO. Usually with an interview completion date within 30 days. SO.... if your son bust's his butt and gets on top of the application as soon as summer seminar is over, he could have at least 3 items on the application finished, and his interview will be probably in August. That's totally up to your son. My son started his application on June 15th; as soon as he returned from Summer Seminar. His application, including the CFA, Medical Exam, ALO interview, and his presidential nomination was 100% complete by the end of July. He spent all of August preparing for early admission apps for other universities and football practices. So, if your son works hard, the ALO interview is not that long from now.
So, in other words, do as your son's ALO requested, and wait until the interview before providing him with all the info your son wants him to know. One of the biggest parts of the military is "Following Instructions". So, as long as your son's ALO isn't holding your son back some how; which would be difficult to do being the ALO isn't the one doing the application, I suggest you follow the ALO's instructions.